OMAP: hwmod/device: add omap_{device,hwmod}_get_mpu_rt_va

Add omap_device_get_mpu_rt_va().  This is intended to be used by
device drivers (currently, via a struct platform_data function
pointer) to retrieve their corresponding device's virtual base address
that the MPU should use to access the device.  This is needed because
the omap_hwmod code does its own ioremap(), in order to gain access to
the module's OCP_SYSCONFIG register.

Add omap_hwmod_get_mpu_rt_va().  omap_device_get_mpu_rt_va() calls this
function to do the real work.

While here, rename struct omap_hwmod._rt_va to struct
omap_hwmod._mpu_rt_va, to reinforce that it refers to the MPU's
register target virtual address base (as opposed to, for example, the
L3's).

In the future, this belongs as a function in an omap_bus, so it is not
necessary to call this through a platform_data function pointer.

The use-case for this function was originally presented by Santosh
Shilimkar <santosh.shilimkar@ti.com>.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
diff --git a/arch/arm/plat-omap/omap_device.c b/arch/arm/plat-omap/omap_device.c
index f9dec0d..dee4629 100644
--- a/arch/arm/plat-omap/omap_device.c
+++ b/arch/arm/plat-omap/omap_device.c
@@ -655,6 +655,25 @@
 	return omap_hwmod_get_pwrdm(od->hwmods[0]);
 }
 
+/**
+ * omap_device_get_mpu_rt_va - return the MPU's virtual addr for the hwmod base
+ * @od: struct omap_device *
+ *
+ * Return the MPU's virtual address for the base of the hwmod, from
+ * the ioremap() that the hwmod code does.  Only valid if there is one
+ * hwmod associated with this device.  Returns NULL if there are zero
+ * or more than one hwmods associated with this omap_device;
+ * otherwise, passes along the return value from
+ * omap_hwmod_get_mpu_rt_va().
+ */
+void __iomem *omap_device_get_rt_va(struct omap_device *od)
+{
+	if (od->hwmods_cnt != 1)
+		return NULL;
+
+	return omap_hwmod_get_mpu_rt_va(od->hwmods[0]);
+}
+
 /*
  * Public functions intended for use in omap_device_pm_latency
  * .activate_func and .deactivate_func function pointers